Estrogen shows an essential modulation effect on various organs in women including the uterus, vagina, skeletal muscles and cardiovascular system, and is primarily responsible for catabolism and activation [Couse and Korach, 1999; Korach et al., 1995]. Thus, estrogen deprivation in women at the menopause causes a variety of medical symptoms called menopausal disorders [Turner et al., 1994; Versi et al., 2001].
A menopausal disorder is a term that refers collectively to various symptoms caused by a sharp reduction of a female hormone (estrogen) in women at the menopause [Dennerstein et al., 2002; Wolff et al., 2006]. To reduce menopausal disorders, hormone therapy has been used to supplement the declining level of female hormones [Greendale et al., 1998; Nichols et al., 1984], but its long-term use causes various adverse effects such as uterus cancer, breast cancer, stroke and pulmonary embolism [Han et al., 2002; Beral et al., 2005; Kaari et al., 2006], so recently, plant-derived phytoestrogens are gaining attention [Knight and Eden, 1996; Setchell, 1998; del Giorno et al., 2010; Ateba et al., 2013]. Phytoestrogens are structurally similar to estrogen so that they can bind to estrogen receptor ER-alpha and ER-beta [Akiyama et al., 1987; Kuiper et al., 1997, Cornwell et al., 2004], showing a weak estrogen-like effect [Kuiper et al., 1997], and they are known as showing an effect on inhibition of various metabolic syndromes in women at the menopause [Taku et al., 2007] as well as a relatively good effect on preservation of bone mass [Ma et al., 2008]. It is known that estrogen deprivation causes significant atrophy of female reproductive organs such as uterus and vagina [Versi et al., 2001; Ateba et al., 2013], and estrogen deficiency induced by OVX also causes significant endometrial atrophy [Kawakita et al., 2009; Ateba et al., 2013].
Osteoporosis is a disorder of bone remodeling characterized by higher bone resorption than bone formation, and a metabolic disease that leads to disorders of mineral metabolism in bodies and drastically increased fractures [Sakai et al., 1998], and particularly, fractures near the hip joint cause so serious problems that threaten lives [Yamaguchi et al., 1999]. OVX rats show extremely similar signs to osteoporosis that develops after women's menopause over 4-6 weeks after operation, and have been very usefully used to develop osteoporosis medicines or bone protective materials [Kalu, 1991; Wronski et al., 1991; Frost and Jee, 1992], and particularly, US Food and Drug Administration suggests OVX rats as an essential animal model to investigate the efficacy in developing osteoporosis medicines [US Food and Drug Administration, 1994]. Reductions in bone weight are directly linked to bone mineral loss caused by the development of osteoporosis [Yamamoto et al., 1998], and particularly, inhibition of ash bone weight reduction is used as a direct evidence showing a treatment effect for osteoporosis [Puel et al., 2005; Xie et al., 2005]. Osteocalcin is used as a typical bone turnover marker, and bALP level is known as a typical bone formation marker in serum [Ke et al., 2004; Rissanen et al., 2008; Yang et al., 2011; Kuo et al., 2012]. Generally, as osteoporosis develops, serum osteocalcin levels increase due to increased bone turnover, serum bALP levels remarkably reduce by inhibition of bone formation [Ismail et al., 1988; Ederveen and Kloosterboer, 1999; Rissanen et al., 2008; Yang et al., 2011; Kuo et al., 2012]. BMD and bone strength are important indices showing the quality of bone, and it is known that osteoporosis causes remarkable reductions in bone mineral density and bone strength regardless of causes [Bilston et al., 2002; Diez, 2002; Syed and Khan, 2002]. A histology test provides most accurate morphological information of bone [Yamaguchi et al., 1999; Heikkinen et al., 2004], and as osteoporosis develops, histomorphometrical indices related to bone mass and bone formation remarkably reduce, and factors related to bone resorption increase [Heikkinen et al., 2004; Jakubas-Przewlocka et al., 2005]. Because remarkable reductions in bone mass and structure and increases in bone resorption activity are histologically confirmed in OVX rats, a histology test of bone always provided a direct efficacy evaluation criterion [Glatt et al., 2004; Jakubas-Przewlocka et al., 2005].